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Received : 12 March 2012; in revised form: 10 April 2012 / Accepted: 17 April 2012 / Published: 8 May 2012 Abstract: Orthosiphon stamineus is considered an important traditional folk medicine. In this study ethanol and aqueous extracts of O. stamineus were evaluated in vitro for their antioxidant, antimicrobial as well as for their immunomodulatory properties on human peripheral blood mononuclear cells (PBMCs). The DPPH radical scavenging method was used for the determination of antioxidant activity, while the antibacterial efficacy was investigated by both disc diffusion method and Minimum Inhibitory Concentration (MIC) against four bacterial strains (Gram-positive and Gram-negative). Furthermore, the immunomodulatory potential of the extracts was investigated through the MTT assay. Aqueous extract of O. stamineus exhibited significant free radical scavenging activity with IC 50 9.6 µg/mL, whereas the IC 50 for the ethanol extract was 21.4 µg/mL. The best antimicrobial activity was shown by the aqueous extract of O. stamineus against Staphylococcus aureus, with inhibition zone of 10.5 mm and MIC value 1.56 mg/mL. OPEN ACCESSMolecules 2012, 17 5386 Moreover, the results observed from the MTT assay showed that both plant extracts stimulated the PBMCs proliferation in vitro in a concentration-dependent manner, but the aqueous extract has remarkable activity against PBMCs. These findings indicate that O. stamineus showed high antioxidant activity and may be considered as an immunomodulatory agent.

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The efficacy of allicin compared with fluconazole in alleviating systemic Candida albicans infections was evaluated both in vitro and in vivo through a systemic candidiasis mouse model. Determination of in vitro minimum inhibitory concentrations (MICs) for different C. albicans isolates revealed that both allicin and fluconazole showed different MICs that ranged from 0.05 to 12.5 μg mL(-1) and 0.25 to 16 μg mL(-1) , respectively. A time-kill study showed a significant effect of allicin (P<0.01) against C. albicans, comparable to that of fluconazole. Scanning electron microscopy observation revealed that, similar to fluconazole, allicin produced structural destruction of C. albicans cell surface at low MIC and lysis or puncture at high MIC concentrations. Treatment of BALB/c mice systemically infected with C. albicans showed that although the allicin treatment (at 5 mg kg(-1) day(-1) ) was slightly less efficacious than fluconazole treatment in terms of the fungal load reduction and host survival time, it was still effective against C. albicans in terms of mean survival time, which increased from 8.4 to 15.8 days. These results demonstrate the efficacy of anticandidal effects of allicin both in vitro and in an animal model of candidiasis and affirm the potential of allicin as an adjuvant therapy to fluconazole.

ObjectivesThis study aimed to evaluate the level of hepatitis B immunity among undergraduate students 23 years after commencement of the nationwide hepatitis B childhood immunization program in Malaysia.MethodsA total of 402 serum samples obtained from volunteer undergraduate students were screened for the presence of hepatitis B surface antibodies using qualitative ELISA.ResultsResults showed that 62.7% of volunteers had protective anti-hepatitis B surface antigens (≥10 IU/L), of whom 67.9% received three doses of the vaccine. The estimated post-vaccination immunity was found to be at least 20 years, indicating persistent immunity against hepatitis B and a significant association (P < 0.05) with duration of vaccination. Anamnestic response 1 month post-hepatitis B booster was 94.0% and highly significant (P < 0.01). Isolated antihepatitis B core antigen (anti-HBc) prevalence was found to be 5.0%, all having had a positive anamnestic response.ConclusionImmunity after primary vaccination with hepatitis B recombinant vaccine persists for at least 20 years post-vaccination, with significant association with the number of vaccinations. Furthermore, the presence of anamnestic response to booster vaccine indicates long-lasting immunity despite decreasing antibody levels; therefore, the need for hepatitis B vaccine boosters may not be of significant benefit after complete infant vaccination.

Hepatitis B virus surface mutants are of enormous importance because they are capable of escaping detection by serology and can infect both vaccinated and unvaccinated populations, thus putting the whole population at risk. This study aimed to detect and characterise hepatitis B-escaped mutants among blood donors and vaccinees. One thousand serum samples were collected for this study from blood donors and vaccinees. Hepatitis B surface antigen, antibodies and core antibodies were tested using a commercial enzyme-linked immunosorbent assay (ELISA) kit. DNA detection was performed via nested polymerase chain reaction (PCR), and the S gene was sequenced and analysed using bioinformatics. Of the 1,000 samples that were screened, 5.5 % (55/1,000) were found to be HBsAg-negative and anti-HBc- and HBV DNA-positive. All 55 isolates were found to belong to genotype B. Several mutations were found across all the sequences from synonymous and non-synonymous mutations, with the most nucleotide mutations occurring at position 342, where adenine was replaced by guanine, and cytosine at position 46 was replaced by adenine in 96.4 % and 98 % of the isolates, respectively. Mutation at position 16 of the amino acid sequence was found to be common to all the Malaysian isolates, with 85.7 % of the mutations occurring outside the major hydrophilic region. This study revealed a prevalence of 5.5 % for hepatitis B-escaped mutations among blood donors and vaccinated undergraduates, with the most common mutation being found at position 16, where glutamine was substituted with lysine.

Background: Occult hepatitis B infections are becoming a major global threat, but the available data on its prevalence in various parts of the world are often divergent. Objective: This study aimed to detect occult hepatitis B virus in hepatitis B surface antigen-negative serum using anti-HBc as a marker of previous infection. Patient and methods: A total of 1000 randomly selected hepatitis B surface antigen-negative sera from blood donors were tested for hepatitis B core antibody and hepatitis B surface antibody using an ELISA and nested polymerase chain reaction was done using primers specific to the surface gene (S-gene). Results: Of the 1000 samples 55 (5.5%) were found to be reactive, of which 87.3% (48/55) were positive for hepatitis B surface antibody, indicating immunity as a result of previous infection however, that does not exclude active infection with escaped mutant HBV. Nested PCR results showed the presence of hepatitis B viral DNA in all the 55 samples that were positive for core protein, which is in agreement with the hepatitis B surface antibody result. Conclusion: This study reveals the 5.5% prevalence of occult hepatitis B among Malaysian blood donors as well as the reliability of using hepatitis B core antibody in screening for occult hepatitis B infection in low endemic, low socioeconomic settings. Malaysia. Afri Health Sci 2016;16(3): 677-683. DOI: Keywords

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